1. Field of the Invention
The present invention generally relates to an apparatus and to a method for treating biological substances by shockwaves or high amplitude acoustic waves. More particularly, the present invention is in the technical field of an apparatus and to a method that use shockwaves for surgery and drug delivery.
2. Description of Related Art
Use of shockwaves or high pressure amplitude acoustic waves in medical procedures is known. U.S. Pat. No. 4,823,773 to G. Naser et al. discloses generation of focused shockwaves with an extracorporeal lithotripter using an array of piezoelectric emitters that allow shattering of calculi in a patient. Extracorporeal shock waves (ESW) can also be generated electro-hydraulically using electrical discharges in liquids as discussed in Patent Application Pub. No. U.S. 2006/0036168 by Shen-Min Liang et al. ESW are used in numerous medical applications including breaking kidney stones, treatment of plantar fasciitis, chronic tendinitis, chronic prostatitis, and other medical conditions (Abstracts, ISMST 10th International ISMST Congress Toronto 2007). ESW cannot be used for treatment of sensitive areas of the body such as the brain due to difficulty in limiting the shockwave effect to a small area. Shock waves generated by ESW devices will lead to rupture of blood vessels, edema, apoptosis and other tissue damage in the large area around the focal point of the device which is not acceptable for most brain treatments.
U.S. Pat. No. 6,562,004 to A. Doukas et al. discloses a device for transdermal drug delivery that uses detonations of solid explosive energetic materials to generate shockwaves that are transmitted into a drug delivery chamber that is in contact with the skin. The device utilizes a single detonation of a layer of solid explosives that are permanently imbedded into the detonation chamber, thus the device is a single action disposable device.
In Patent Application Publication No. U.S. 2007/0239082, R. Schultheiss et al. disclose a system for treating an internal organ that has a generator source for producing a shock wave connected to a handheld or small shock wave applicator device. The shockwaves are generated by an electrical discharge in liquid contained in the shock wave applicator device and transmitted to the internal organs through a membrane where some areas of the devices are shielded with shock wave absorbing materials or an air gap. External shockwave generation devices based on electrical discharge are not desirable because of damage that can be inflicted to large areas at high pressure levels. In U.S. Patent Application Publication No. U.S. 2006/0036195 R. Schultheiss et al. disclose devices for shock therapy for organs where the entire piezo-ceramic pressure/shockwave generation devices are directly inserted near or into internal organs which is undesirable because it presents a number of limitations on device size and, shockwave intensity and other parameters.
In U.S. Patent Application Publication No. U.S. 2009/0221940, E. H. Marlinghoust et al. disclose an apparatus that generates shock waves by a projectile that collides into an impact body that transmits shock waves into a biological substance. The device produces so called radial shock waves that expand outward from the contact point with the device. The shock waves generated by such a device will have low amplitude and relatively large durations because of inertia of the mechanical projectile.
In U.S. Patent Application Publication No. U.S. 2011/0034832, I. Cioanta et al. disclose a shock wave applicator that includes a shock wave generator and an asymmetrical reflector that enables focusing shock waves at different parts of the body. Although the merits and physics of shock generation or shock reflection are not shown, this patent application describes possible uses of shock waves in medical procedures including: use of shock waves to destroy plaque in blood vessels, treatment of heart muscles, removal of fluid accumulation in the heart, a combination of shockwave treatment with drugs for removing plaque from blood vessels, use of shock waves for dissolution of fat cells, use of shockwaves to create and increase circulation in the colon, and the use of shock waves to promote healing.
U.S. Pat. No. 5,947,928 to D. F. Muller discloses a drug delivery system including a drug delivery initiator for generating a shock wave and a membrane receiving the shock wave and transmitting the shock wave to a material. In operation, rapid opening of a divider causes a shock wave to be generated as pressurized gas is released from the proximal chamber into the distal chamber. The shock wave is then transmitted through the distal opening of the initiator to impinge on the membrane which, in turn, transfers the shock wave to the biological material. Impact of the shock wave on the skin increases the porosity of any of the bio-membranes at or below the skin, thereby enhancing absorption of the drug. In this type of device, the peak pressure as well as shockwave duration will be limited by the pressure difference and rate of opening of the divider between the chambers. The rate of the pressure rise facilitated by the valves will not be sufficient for creation of shockwaves that typically have less than microseconds for the pressure to rise form ambient to peak values. Use of a bursting membrane between the proximal and distal chambers will increase the rate of pressure increase, however it will allow only a single shock wave creation, thus making this device a single use device.
The field of applications of the shock waves in medicine is very broad and includes drug delivery, killing cancer cells, promoting bone healing and others. However, despite the clearly demonstrated effectiveness of using high-intensity shockwaves for medical applications, in practice the use of shockwaves is limited to ether breaking kidney stones where damage to surrounding tissue can be tolerated, or treatment of plantar fasciitis and chronic tendinitis where multiple small energy shockwaves are applied for general stimulation and pain relief. Use of shockwaves for killing cancer cells and bacteria in the internal organs although shown in in vitro studies (S. Bao, B. D. Thrall, R. A. Gies, and D. L. Miller, In Vivo Transfection of Melanoma Cells by Lithotripter Shock Waves, Cancer Research 58, 219-221, Jan. 15, 1998.) is not practical due to lack of capability to generate and deliver high intensity shock waves with high spatial accuracy to the targeted area. Drug delivery using shock waves was demonstrated only for transdermal delivery using laser generated shock waves (T. Kodama, A. G. Doukas, M. R. Hamblin, Delivery of ribosome-inactivating protein toxin into cancer cells with shock waves, Cancer Letters 189, 69-75, 2003.). This technique cannot be applied for drug delivery to internal organs. Use of electromechanical transducers, pressure driven pellets, or electric discharge limit pressure amplitude, shock waves durations and accuracy of shockwave targeting which limits their applications. Use of solid explosive or other high energy density material as disclosed in U.S. Pat. No. 6,562,004 for drug delivery is dangerous and impractical because of regulations governing use and applications of solid explosives. Also use of explosives leads to a single action device which is not practical for many applications.
Thus, there is a critical need for efficient generation of high intensity shockwaves for medical applications. The present invention contemplates elimination of the drawbacks associated with prior art apparatus and methods for generating shockwaves for medical applications.
It is therefore an object of the present invention to provide a method and apparatus for efficient generation of shockwaves with a wide range of amplitudes and positive phase durations and the accurate delivery of such shockwaves to targeted internal or external body area.
It is another object of the present invention to provide a method and apparatus for surgery and drug delivery locally and systemically that will enable direct application of high-intensity shockwaves to cancer tumors or other areas of the body through small-diameter shockwaves guides.
A further object of the present invention is to provide a method and apparatus for surgery that will enable direct delivery of shockwaves wherein the peak pressure and impulse can be adjusted based on application need.
Another object of the present invention is to provide a method and apparatus for surgery and drug delivery locally and systemically that can be image guided to treat different areas of the body.
Another object of the present invention is to provide a method and apparatus that will allow application of shockwaves while preserving or minimizing damage to eloquent areas of the internal organs such as the brain or others where the areas adjacent to a target intended for shockwaves treatment will not be damaged.
Another object of the present invention is to provide a method and apparatus that will be compatible with MRI or similar visualization technology.